The present invention relates to a voltage detection device for detecting voltage of a battery pack and to an electric vehicle incorporating the voltage detection device.
Japanese Laid-Open Patent Publication No. 2002-040064 describes a device for detecting voltage of a battery block in a battery pack.
In detail, Japanese Laid-Open Patent Publication No. 2002-040064 describes a battery voltage detection device including a single capacitor connected in parallel to a reference voltage generator. The reference voltage generator includes a constant voltage step-down circuit, such as a zener diode. In the battery voltage detection device, a switch is used to charge the capacitor with a rechargeable battery included in the battery pack. A voltage detector of the battery voltage detection device is supplied with reference voltage, or the voltage across the charged capacitor, to correct an internal reference voltage.
In the prior art, the battery voltage detection device is not connected to a reference voltage generation power supply. This is advantageous in that the internal reference voltage can be solely and frequently corrected. However, the battery voltage detection device cannot generate an internal reference voltage that is greater than or equal to the step down voltage of the zener diode, which functions as the constant voltage step-down circuit.
Therefore, when detecting a relatively high battery block voltage with the battery voltage detection device of the prior art, detection errors cannot be accurately corrected.